.highlighting{
  border-radius: 5px;
  padding: 15px;
  animation: alphaNum 2s infinite alternate;
}

@keyframes alphaNum {
  0%{
    box-shadow: inset 0px 0px 20px rgba($color: #fff, $alpha: 0);
  }
  100%{
    box-shadow: inset 0px 0px 20px rgba($color: #fff, $alpha: 1);
  }
}